Nah, that's looser than you think. Contractors deploy to the government cloud regions on AWS and Azure all the time. There's no reason GitLab can't become a qualified contractor and gain access.
The government cloud regions are way more about meeting compliance with all levels of FedRAMP and DoD requirements. Such as exclusively only US Citizens may access the systems even on the cloud hosts staff (so no foreign/remote/visa employees) and a whole list of other requirements both big, small and annoying (like FIPS) that affects everything from software to the physical building.
The government cloud regions are way more about meeting compliance with all levels of FedRAMP and DoD requirements. Such as exclusively only US Citizens may access the systems even on the cloud hosts staff (so no foreign/remote/visa employees) and a whole list of other requirements both big, small and annoying (like FIPS) that affects everything from software to the physical building.